/* Neural Forge AI - Design System & Styles */

/* ============================================
   DESIGN TOKENS
   ============================================ */
:root {
  /* Colors - Brand */
  --color-primary-dark: #0A2463;
  --color-primary: #1E88E5;
  --color-primary-light: #42A5F5;
  
  /* Colors - Neutrals */
  --color-bg: #FFFFFF;
  --color-bg-alt: #F8F9FA;
  --color-surface: #FFFFFF;
  --color-text: #1A1A1A;
  --color-text-secondary: #6B7280;
  --color-border: #E5E7EB;
  
  /* Colors - Semantic */
  --color-success: #10B981;
  --color-error: #EF4444;
  --color-warning: #F59E0B;
  
  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Courier New', monospace;
  
  --font-size-xs: 0.75rem;    /* 12px */
  --font-size-sm: 0.875rem;   /* 14px */
  --font-size-base: 1rem;     /* 16px */
  --font-size-lg: 1.125rem;   /* 18px */
  --font-size-xl: 1.25rem;    /* 20px */
  --font-size-2xl: 1.5rem;    /* 24px */
  --font-size-3xl: 1.875rem;  /* 30px */
  --font-size-4xl: 2.25rem;   /* 36px */
  --font-size-5xl: 3rem;      /* 48px */
  
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  
  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;
  
  /* Spacing */
  --space-xs: 0.25rem;   /* 4px */
  --space-sm: 0.5rem;    /* 8px */
  --space-md: 1rem;      /* 16px */
  --space-lg: 1.5rem;    /* 24px */
  --space-xl: 2rem;      /* 32px */
  --space-2xl: 3rem;     /* 48px */
  --space-3xl: 4rem;     /* 64px */
  --space-4xl: 6rem;     /* 96px */
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  --shadow-glow: 0 0 0 3px rgba(30, 136, 229, 0.2);
  
  /* Border Radius */
  --radius-sm: 0.25rem;  /* 4px */
  --radius-md: 0.5rem;   /* 8px */
  --radius-lg: 0.75rem;  /* 12px */
  --radius-xl: 1rem;     /* 16px */
  
  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-base: 250ms ease-in-out;
  --transition-slow: 350ms ease-in-out;
  
  /* Layout */
  --container-max: 1280px;
  --container-padding: var(--space-md);
  --nav-height: 64px;
}

/* Dark Mode Tokens */
[data-theme="dark"] {
  --color-bg: #0F172A;
  --color-bg-alt: #1E293B;
  --color-surface: #1E293B;
  --color-text: #F1F5F9;
  --color-text-secondary: #94A3B8;
  --color-border: #334155;
}

/* ============================================
   RESET & BASE STYLES
   ============================================ */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   TYPOGRAPHY
   ============================================ */
h1, h2, h3, h4, h5, h6 {
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  margin-bottom: var(--space-md);
}

h1 { font-size: var(--font-size-5xl); }
h2 { font-size: var(--font-size-4xl); }
h3 { font-size: var(--font-size-3xl); }
h4 { font-size: var(--font-size-2xl); }
h5 { font-size: var(--font-size-xl); }
h6 { font-size: var(--font-size-lg); }

p {
  margin-bottom: var(--space-md);
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-primary-light);
}

/* ============================================
   LAYOUT COMPONENTS
   ============================================ */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

/* Navigation */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  height: var(--nav-height);
  display: flex;
  align-items: center;
  backdrop-filter: blur(10px);
  background-color: rgba(255, 255, 255, 0.95);
}

[data-theme="dark"] .nav {
  background-color: rgba(30, 41, 59, 0.95);
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-primary-dark);
}

.nav-logo svg {
  width: 32px;
  height: 32px;
}

.nav-links {
  display: flex;
  gap: var(--space-xl);
  list-style: none;
  align-items: center;
}

.nav-links a {
  color: var(--color-text);
  font-weight: var(--font-weight-medium);
  transition: color var(--transition-fast);
}

.nav-links a:hover {
  color: var(--color-primary);
}

.nav-cta {
  background: linear-gradient(135deg, var(--color-primary-dark), var(--color-primary));
  color: white;
  padding: var(--space-sm) var(--space-lg);
  border-radius: var(--radius-md);
  font-weight: var(--font-weight-semibold);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.nav-cta:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  color: white;
}

/* Mobile Menu Toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
  color: var(--color-text);
}

.nav-toggle svg {
  width: 24px;
  height: 24px;
}

/* Footer */
.footer {
  background-color: var(--color-bg-alt);
  border-top: 1px solid var(--color-border);
  padding: var(--space-3xl) 0 var(--space-xl);
  margin-top: var(--space-4xl);
}

.footer-content {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-2xl);
  margin-bottom: var(--space-2xl);
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-primary-dark);
}

.footer-tagline {
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
}

.footer-section h4 {
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-semibold);
  margin-bottom: var(--space-md);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-secondary);
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.footer-links a {
  color: var(--color-text);
  font-size: var(--font-size-sm);
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: var(--color-primary);
}

.footer-bottom {
  padding-top: var(--space-xl);
  border-top: 1px solid var(--color-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
}

.footer-social {
  display: flex;
  gap: var(--space-md);
}

.footer-social a {
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
}

.footer-social a:hover {
  color: var(--color-primary);
}

/* ============================================
   HERO SECTION
   ============================================ */
.hero {
  background: linear-gradient(135deg, var(--color-primary-dark), var(--color-primary));
  color: white;
  padding: var(--space-4xl) 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
  opacity: 0.3;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
  margin: 0 auto;
}

.hero h1 {
  font-size: var(--font-size-5xl);
  margin-bottom: var(--space-lg);
  line-height: 1.1;
}

.hero p {
  font-size: var(--font-size-xl);
  opacity: 0.95;
  margin-bottom: var(--space-2xl);
  line-height: var(--line-height-relaxed);
}

/* ============================================
   CARD COMPONENTS
   ============================================ */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--space-xl);
  margin-top: var(--space-2xl);
}

.card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  transition: transform var(--transition-base), box-shadow var(--transition-base);
  cursor: pointer;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-xl);
}

.card-category {
  display: inline-block;
  padding: var(--space-xs) var(--space-md);
  background-color: rgba(30, 136, 229, 0.1);
  color: var(--color-primary);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-xs);
  font-weight: var(--font-weight-semibold);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-md);
}

.card h3 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--space-md);
  color: var(--color-text);
}

.card-summary {
  color: var(--color-text-secondary);
  margin-bottom: var(--space-lg);
  line-height: var(--line-height-relaxed);
}

.card-meta {
  display: flex;
  gap: var(--space-lg);
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  padding-top: var(--space-md);
  border-top: 1px solid var(--color-border);
}

.card-meta-item {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

/* ============================================
   BUTTONS
   ============================================ */
.btn {
  display: inline-block;
  padding: var(--space-md) var(--space-xl);
  border-radius: var(--radius-md);
  font-weight: var(--font-weight-semibold);
  font-size: var(--font-size-base);
  text-align: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  border: none;
  text-decoration: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-primary-dark), var(--color-primary));
  color: white;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  color: white;
}

.btn-secondary {
  background-color: transparent;
  border: 2px solid var(--color-primary);
  color: var(--color-primary);
}

.btn-secondary:hover {
  background-color: var(--color-primary);
  color: white;
}

.btn:focus {
  outline: none;
  box-shadow: var(--shadow-glow);
}

/* ============================================
   FORMS
   ============================================ */
.form-group {
  margin-bottom: var(--space-lg);
}

.form-label {
  display: block;
  font-weight: var(--font-weight-medium);
  margin-bottom: var(--space-sm);
  color: var(--color-text);
}

.form-input {
  width: 100%;
  padding: var(--space-md);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  background-color: var(--color-surface);
  color: var(--color-text);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: var(--shadow-glow);
}

.form-input::placeholder {
  color: var(--color-text-secondary);
}

/* ============================================
   CODE BLOCKS
   ============================================ */
code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background-color: var(--color-bg-alt);
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-sm);
}

pre {
  background-color: var(--color-primary-dark);
  color: #E5E7EB;
  padding: var(--space-xl);
  border-radius: var(--radius-lg);
  overflow-x: auto;
  margin-bottom: var(--space-lg);
}

pre code {
  background: none;
  padding: 0;
  color: inherit;
}

/* ============================================
   SECTIONS
   ============================================ */
.section {
  padding: var(--space-4xl) 0;
}

.section-header {
  text-align: center;
  max-width: 700px;
  margin: 0 auto var(--space-3xl);
}

.section-title {
  font-size: var(--font-size-4xl);
  margin-bottom: var(--space-md);
  color: var(--color-text);
}

.section-subtitle {
  font-size: var(--font-size-lg);
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

/* ============================================
   NEWSLETTER CTA
   ============================================ */
.newsletter-cta {
  background: linear-gradient(135deg, var(--color-primary-dark), var(--color-primary));
  color: white;
  padding: var(--space-3xl);
  border-radius: var(--radius-xl);
  text-align: center;
  margin-top: var(--space-4xl);
}

.newsletter-cta h2 {
  font-size: var(--font-size-3xl);
  margin-bottom: var(--space-md);
}

.newsletter-cta p {
  font-size: var(--font-size-lg);
  opacity: 0.95;
  margin-bottom: var(--space-xl);
}

.newsletter-form {
  display: flex;
  gap: var(--space-md);
  max-width: 500px;
  margin: 0 auto;
}

.newsletter-form .form-input {
  flex: 1;
  background-color: white;
}

/* ============================================
   FEATURE GRID
   ============================================ */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-2xl);
  margin-top: var(--space-3xl);
}

.feature-card {
  text-align: center;
  padding: var(--space-xl);
}

.feature-icon {
  width: 48px;
  height: 48px;
  margin: 0 auto var(--space-lg);
  color: var(--color-primary);
}

.feature-card h3 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--space-md);
}

.feature-card p {
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

/* ============================================
   FILTER BAR
   ============================================ */
.filter-bar {
  display: flex;
  gap: var(--space-md);
  margin-bottom: var(--space-2xl);
  flex-wrap: wrap;
}

.filter-btn {
  padding: var(--space-sm) var(--space-lg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background-color: var(--color-surface);
  color: var(--color-text);
  cursor: pointer;
  font-weight: var(--font-weight-medium);
  transition: all var(--transition-fast);
}

.filter-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.filter-btn.active {
  background-color: var(--color-primary);
  color: white;
  border-color: var(--color-primary);
}

/* ============================================
   DARK MODE TOGGLE
   ============================================ */
.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
  color: var(--color-text);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: color var(--transition-fast);
}

.theme-toggle:hover {
  color: var(--color-primary);
}

.theme-toggle svg {
  width: 20px;
  height: 20px;
}

/* ============================================
   UTILITY CLASSES
   ============================================ */
.text-center { text-align: center; }
.text-primary { color: var(--color-primary); }
.text-secondary { color: var(--color-text-secondary); }

.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mt-xl { margin-top: var(--space-xl); }
.mt-2xl { margin-top: var(--space-2xl); }

.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.mb-xl { margin-bottom: var(--space-xl); }
.mb-2xl { margin-bottom: var(--space-2xl); }

/* ============================================
   RESPONSIVE BREAKPOINTS
   ============================================ */

/* Tablet: 768px */
@media (max-width: 768px) {
  :root {
    --font-size-5xl: 2.5rem;
    --font-size-4xl: 2rem;
    --font-size-3xl: 1.5rem;
  }
  
  .nav-links {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background-color: var(--color-surface);
    flex-direction: column;
    padding: var(--space-xl);
    gap: var(--space-lg);
    transform: translateX(-100%);
    transition: transform var(--transition-base);
    box-shadow: var(--shadow-lg);
  }
  
  .nav-links.active {
    transform: translateX(0);
  }
  
  .nav-toggle {
    display: block;
  }
  
  .card-grid {
    grid-template-columns: 1fr;
  }
  
  .footer-content {
    grid-template-columns: 1fr;
    gap: var(--space-xl);
  }
  
  .footer-bottom {
    flex-direction: column;
    gap: var(--space-md);
    text-align: center;
  }
  
  .newsletter-form {
    flex-direction: column;
  }
  
  .hero {
    padding: var(--space-3xl) 0;
  }
  
  .section {
    padding: var(--space-3xl) 0;
  }
}

/* Mobile: 375px */
@media (max-width: 480px) {
  :root {
    --font-size-5xl: 2rem;
    --font-size-4xl: 1.75rem;
    --space-4xl: 3rem;
    --container-padding: var(--space-md);
  }
  
  .feature-grid {
    grid-template-columns: 1fr;
  }
}

/* Large Desktop: 1440px+ */
@media (min-width: 1440px) {
  :root {
    --container-max: 1400px;
  }
  
  .card-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* ============================================
   ANIMATIONS
   ============================================ */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in {
  animation: fadeIn 0.6s ease-out;
}

/* ============================================
   LOADING STATE
   ============================================ */
.loading {
  display: inline-block;
  width: 20px;
  height: 20px;
  border: 3px solid rgba(255, 255, 255, 0.3);
  border-radius: 50%;
  border-top-color: white;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ============================================
   ACCESSIBILITY
   ============================================ */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* Focus visible for keyboard navigation */
*:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}